Research on the influence mechanism of internal flow characteristics on energy conversion in radial energy recovery turbines under multiple conditions

Abstract

The development of Energy Recovery Turbine (ERT) is of great significance for energy saving and emission reduction. The mutual influence mechanism between the flow characteristics and energy conversion of ERT has not yet been mastered. A radial ERT was selected as the research object and a mathematical model based on entropy generation theory was established to evaluate the energy loss of the ERT. The internal flow characteristics and energy loss mechanism of an ERT were studied. The results show that the entropy generation power of the impeller accounts for 17.4 %. The turbulent entropy generation power of the impeller accounts for 76.5 % of the total entropy generation power. The energy loss at the volute tongue is maximized due to the presence of two attached vortexes with opposite rotation directions. The area with significant energy loss in the impeller gradually shifts from hub and pressure surface to the suction surface as the flow increases. The performance degradation under overload conditions is relatively slow, as the flow impact on the pressure surface has a smaller impact on the blade's ability to perform work. Therefore, the hydraulic design should be carried out after appropriately reducing the rated flow rate when designing a radial turbine.